Elasmobranchii (sharks and rays) >
Rajiformes (Skates and rays) >
Arhynchobatidae (Softnose skates)
Etymology: Bathyraja: Greek, bathys = deep + Latin, raja, -ae = a ray (Raja sp) (Ref. 45335); microtrachys: Name from Latin 'micro' meaning small, and 'trachys' meaning spine, referring to the uniform fine prickles covering the dorsal surface.
Environment: milieu / climate zone / depth range / distribution range
Ecology
Marine; bathydemersal; depth range 1995 - 3000 m (Ref. 126515), usually 2000 - 3000 m (Ref. 126515). Temperate
Northeastern Pacific: from British Columbia, south to the Gulf of California
Size / Weight / Age
Maturity: Lm ? range ? - ? cm
Max length : 75.0 cm TL male/unsexed; (Ref. 126515)
Short description
Identification keys | Morphology | Morphometrics
This moderate sized, rhomboidal skates (91.0 cm TL), with disc length (41.5-51.1% TL), head moderately long (18.3-21.2% TL), internarial distance large (7.3-8.7% TL) is distinguished by the following: claspers short and robust, tip rounded, with very large pseudosiphon and a long, slender pseudorhipidion nearly reaching the tip, V-shaped cleft, no projection; teeth in 23-30 rows on upper jaw and 11-22 rows on lower jaw; pectoral radials 61-74; pelvic fins 14; total vertebrae 130; its dorsal surface evenly covered in fine prickles; thorns on dorsal surface, males with alar thorns, but without malar thorns, middorsal, nuchal, and scapular thorns absent, tail thorns high in number (19-26); interdorsal thorns weak to obsolete (0-1). Colouration: dorsal uniformly brown, usually darker at the margins while ventral is white, brown pectorals and pelvic fins (Ref. 126515).
This species inhabits perhaps the deepest waters and prefer low temperature, high oxygen environments compared to its congeners. Little is known about the diet of this species, except noted to consume deep-water shrimps. Based on materials examined, size at maturity for males is at least 64-75 cm TL and 60-70 cm TL for females; with reported size at birth to be about 17 cm TL. Egg cases are small (7.9-8.1 cm TL), dark golden brown in colour, coarsely striated with irregular rasp-like denticles, making it rough to the touch. Horns at the corners with the anterior ones robust at base, but flatten towards tips and the tips curve dorsally and back towards the egg case (Ref. 126515).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Knuckey, J.D.S. and D.A. Ebert, 2022. A taxonomic revision of Northeast Pacific softnose skates (Rajiformes: Arhynchobatidae: Bathyraja Ishiyama). Zootaxa 5142(1):1-89. (Ref. 126515)
IUCN Red List Status (Ref. 130435: Version 2024-1)
Threat to humans
Harmless
Human uses
Fisheries: of no interest
Tools
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Internet sources
Estimates based on models
Phylogenetic diversity index (Ref.
82804): PD
50 = No PD50 data [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00550 (0.00291 - 0.01038), b=3.13 (2.97 - 3.29), in cm total length, based on LWR estimates for this Genus-body shape (Ref.
93245).
Trophic level (Ref.
69278): 3.9 ±0.7 se; based on size and trophs of closest relatives
Resilience (Ref.
120179): Low, minimum population doubling time 4.5 - 14 years (Preliminary K or Fecundity.).
Fishing Vulnerability (Ref.
59153): Moderate to high vulnerability (50 of 100).
